The main advantage of Roots vacuum pump is that it can operate with high pumpingspeed under lower suction pressures&comma; however&comma; has to be backed by a backing pump&period;&lpar;See Fig&period;3&rpar; Under normal working conditions&comma; it is permissible to not add by-pass pipes&period;Roots vacuum pump should not operate with a higher-pressure difference than allowable&comma;otherwise overheating and overload will cause damage of Roots vacuum pump&period;Therefore&comma; proper backing pump and necessary protection devices must be considered&period;

Model

ZJB-30

ZJB-70

ZJB-150

ZJB-300

ZJB-600

ZJB-1200

Extract Capacity &lpar;L&sol;S&rpar;

30

70

150

300

600

1200

Ultimate Vacuum&lpar;Pa&rpar;

≤3&ast;10-2

RPM&lpar;r&sol;min&rpar;

2770

2870

2900

1450

2900

1450

Motor&lpar;Kw&rpar;

0&period;75

1&period;5

3

4

5&period;5

11

Noise dB&lpar;A&rpar;

≤78

≤78

≤82

≤83

≤86

≤90

Inlet diameter &lpar;mm&rpar;

50

80

100

150

150

300

Outlet diameter &lpar;mm&rpar;

40

50

100

150

150

300

Weight &lpar;Kg&rpar;

75

100

215

480

503

1580

NOTES&colon;1&period; Ultimate pressure &lpar;Pa&rpar; value is measured by mercury McLeod vacuum gauge&period;2&period; Pumping speed refers to maximum pumping speed measured when Roots vacuumpump is connected with a recommended backing pump with an inlet pressure rangingfrom 67Pa to 2&period; 7Pa&period;73&period; Ultimate pressure refers to lowest value of stable partial pressure measured at inletport of a Roots pump without any additional vessels after sufficient suction with inletof it tightly closed by a blank flange when connected with a recommended backingpump&period;4&period; Each performance above the list is obtained under recommended backing pump&period;Customers can select backing pump suitable for the intended application&comma; but its mainperformance index may have some changes&period;